The present invention relates generally to nonwoven fabrics exhibiting elasticity, and more particularly to a hydroentangled nonwoven fabric exhibiting extensibility and recovery in the cross-direction, and a method of making same. A mattress pad assembly including the present nonwoven fabric is also disclosed.
Nonwoven fabrics are used in a very wide variety of applications where the engineered qualities of the fabric can be advantageously employed. These type of fabrics differ from traditional woven or knitted fabrics in that the fibers or filaments of the fabric are integrated into a coherent web without traditional textile processes. Entanglement of the fibers or filaments of the fabric provide the fabric with the desired integrity, with the application of binder compositions and the like being well-known for further enhancing the integrity of the structure.
Various parameters impact the physical characteristics of the nonwoven fabric, including fiber composition and size, fiber orientation, fiber entanglement, and integration of the fibers such as by application of binders or thermal bonding. Variations in these parameters permit fabrics to be engineered for specific applications, thus enhancing the cost-effectiveness of such materials.
While fabrics of this nature have found wide-spread applicability, the nature of the processes by which they are typically formed can limit the uses for which particular fabrics are suited. Ordinarily, fabrics are manufactured so as to exhibit a xe2x80x9cmachine directionxe2x80x9d (MD), extending along the length of the fabric in the direction in which it is manufactured, and a xe2x80x9ccross-directionxe2x80x9d (CD) extending perpendicularly to the machine direction. While fabrics can be engineered to exhibit certain properties, these fabrics ordinarily do not exhibit a relatively high degree of recovery, after extension, in the cross-direction.
The present invention is directed to a nonwoven fabric exhibiting cross-direction extensibility and recovery, a method of making the fabric, and a mattress pad assembly for which the present fabric is particularly suited for use.
The present hydroentangled (spun-laced) nonwoven fabric has been particularly configured to exhibit elastic characteristics, that is, extensibility and recovery, in the cross-direction of the fabric. The cross-direction (CD) is transverse or perpendicular to the machine-direction (MD) of the fabric, that is, the direction in which the fabric is manufactured and processed, typically extending along the longitudinal axis of the fabric. By configuring the present fabric to exhibit cross-direction elasticity, the fabric can be employed in those applications in which such elastic characteristics are desirable.
A nonwoven fabric embodying the principles of the present invention comprises a hydroentangled nonwoven web preferably comprising staple length textile fibers of about 0.8 to 3.0 denier having a basis weight of about 1.0 to 6.0 ounces per square yard, preferably 2.0 to 4.0 ounces per square yard. More preferably, the nonwoven web comprises fibers of about 1.5 denier, with the web having a basis weight of about 2.5 to 3.5 ounces per square yard. Use of polyester fibers is presently preferred, but it is within the purview of the present invention to form the present nonwoven fabric from blends which include at least a portion of synthetic fibers blended with natural fibers, and from substantially continuous filaments.
The nonwoven web is subjected to hydroentanglement in order to entangle and integrate the fibers of the web, and thus lend integrity to the structure. In a current preferred embodiment, hydroentanglement is effected so as to impart a rectilinear pattern to the nonwoven web, which pattern is preferably oriented at an angle between about 30xc2x0 and 60xc2x0 relative to a machine-direction of the web. In a preferred method of formation, the nonwoven web is subjected to preliminary hydroentanglement to lend integrity thereto prior to formation of the rectilinear pattern in the web by hydroentanglement on a patterned forming surface.
In order to impart elastomeric characteristics to the fabric formed by hydroentanglement, a polymeric binder composition is substantially uniformly applied to the nonwoven fabric. Although the specific amount of binder can be varied while keeping with the principles disclosed herein, it is presently preferred that the binder composition comprise between about 17% and about 31%, by weight, of acrylic binder. Subsequent to application of the polymeric binder composition, the nonwoven web is dried to form the present nonwoven fabric. Significantly, the resultant nonwoven fabric exhibits elastomeric characteristics (i.e., stretch or extensibility, and recovery) in the cross-direction of the fabric. In accordance with the present invention, the fabric exhibits at least about 20% extensibility in the cross-direction, and at least about 90% recovery in the cross-direction, preferably at least about 50% extensibility in the cross-direction, with at least about 90% recovery. The fabric is thus engineered to exhibit a relatively high degree of cross-direction elasticity.
By virtue of the elastic characteristics of the present nonwoven fabric, the fabric can be employed in a wide variety of applications as a substitute for knit or woven fabrics in applications where stretch recovery characteristics are desirable. In a current application of the present fabric, the fabric is advantageously employed in a mattress pad assembly. Heretofore, such articles have typically required combinations of fabric panels and stretchable components fitted about the periphery of an associated upper mattress pad. A mattress pad assembly employing the present nonwoven fabric includes a generally rectangular upper pad, and a peripheral nonwoven fabric extending about and secured to the upper pad at the periphery thereof. The fabric can be formed in accordance with the present invention, and is preferably provided in the form of a single piece of material extending about the periphery of the upper pad. At least one elongate elastic member can be provided secured to the nonwoven fabric at a marginal portion thereof opposite the upper pad, with the resultant assembly being desirably straightforward in configuration for desirably reduced manufacturing costs.
As will be evident from the following detailed description, the desired elastomeric properties for the present nonwoven web can be achieved by various combinations of fiber orientation, pattern entanglement, and binder composition add-on. This further facilitates engineering the present web material for various types of applications while still achieving the desired elastic characteristics.
Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.